U.S. patent number 5,106,308 [Application Number 07/663,976] was granted by the patent office on 1992-04-21 for planar contact grid array connector.
This patent grant is currently assigned to Allied-Signal Inc.. Invention is credited to Bernard P. Gollomp, Bruce E. Kurtz.
United States Patent |
5,106,308 |
Gollomp , et al. |
April 21, 1992 |
Planar contact grid array connector
Abstract
A planer contact grid array connector features a selectively
ceramic coated metal substrate in combination with ceramic thick
film and/or multi-layer thin film circuitry and contacts of various
configurations which may be affixed to or incorporated in mating
connector halves. Planer contact array connectors of the type
described have coaxial connection features, increased power
handling capability and improved means for effecting gas-tight
contact between mating connector halves. Additionally, the
connectors are more reliable, lighter and more rugged than
currently available connectors and have the capability of
incorporating integral ceramic thick film components such as
capacitors and resistors for filtering, impedance control and
signal/power conditioning, as the case may be.
Inventors: |
Gollomp; Bernard P. (West
Lawrence, NY), Kurtz; Bruce E. (Lebanon, NJ) |
Assignee: |
Allied-Signal Inc. (Morris
Township, Morris County, NJ)
|
Family
ID: |
24663994 |
Appl.
No.: |
07/663,976 |
Filed: |
March 4, 1991 |
Current U.S.
Class: |
439/67;
174/252 |
Current CPC
Class: |
H01R
12/57 (20130101); H01R 13/719 (20130101); H05K
3/325 (20130101); H05K 3/445 (20130101); H05K
1/053 (20130101); H05K 1/092 (20130101); H05K
1/095 (20130101); H05K 1/16 (20130101); H05K
2201/09809 (20130101); H05K 3/4007 (20130101); H05K
3/4608 (20130101); H05K 3/4676 (20130101); H05K
3/28 (20130101) |
Current International
Class: |
H01R
13/719 (20060101); H05K 3/44 (20060101); H05K
3/32 (20060101); H05K 3/40 (20060101); H05K
1/16 (20060101); H05K 1/05 (20060101); H05K
1/09 (20060101); H05K 3/46 (20060101); H05K
1/00 (20060101); H05K 3/28 (20060101); H01R
009/09 () |
Field of
Search: |
;439/74,85,67,85
;361/386,387,414 ;174/252,256 ;29/830,831,846,852 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Abrams; Neil
Attorney, Agent or Firm: Massung; Howard G. Walsh; Robert
A.
Claims
What is claimed is:
1. A planar contact grid array connector, comprising:
a metal core;
a ceramic dielectric coating selectively disposed on at least one
side of the metal core so that portions of the at least one side of
the metal core do not have the ceramic dielectric coating thereon,
with said metal core and ceramic dielectric coating disposed
thereon providing a substrate;
circuitry provided on the ceramic dielectric coating, with said
circuitry and substrate providing one half of a connector pair,
said circuitry including ceramic thick film circuit means disposed
on top of the ceramic dielectric coating, and polymer dielectric
means with thick film metal conductor means disposed on top of the
ceramic thick film circuit means and including a plurality of
layers and means provided in the polymer dielectric means for
interconnecting said plurality of layers;
conductive through holes provided in the substrate at locations
where coaxial connections are required;
polymer dielectric means for insulating the coaxial connection
conductive through holes from the metal core;
center conductors of coaxial connections extending through the
substrate;
polymer dielectric means for insulating the center conductors from
the conductive through holes;
annular pads on the surface of the ceramic dielectric coating
connected to the conductive through holes;
center pads on the surface of the ceramic dielectric coating
connected to the center conductors;
mating circuitry disposed over the circuitry provided on the
ceramic dielectric coating;
a compliant member disposed over the mating circuitry, with said
compliant member and mating circuitry forming the other half of the
connector pair;
a backing plate disposed over the compliant member; and
a clamping force applied to the metal core of the substrate and to
the backing plate for engaging and aligning the one and the other
halves of the connector pair, with the compliant member ensuring a
uniform distribution of the clamping force over the mating
circuitry.
2. A connector as described by claim 1, wherein the mating
circuitry includes:
polymer dielectric means;
pads on the surface of the polymer dielectric means corresponding
to and mating with corresponding annular and center pads on the
surface of the ceramic dielectric coating; and
the outer pads on the surface of the ceramic dielectric coating
being thereby connected to a conductor within the polymer
dielectric means, and the annular pads on said ceramic dielectric
coating surface being connected to shield layers within the polymer
dielectric means.
Description
BACKGROUND OF THE INVENTION
This invention relates to a planar contact grid array connector
having a metal substrate selectively coated with a ceramic, in
combination with ceramic thick film and/or multi-layer thin film
circuitry and contacts which may be affixed to or incorporated in
mating connector halves.
Planar contact grid array connectors of the type described feature
the following characteristics: increased power handling capability;
improved means for effecting gas-tight contact between mating
connector halves; a more rugged, more reliable, lighter and smaller
connector than has heretofore been known; coaxial connection
features; and integral means for electromagnetic interference (EMI)
filtering, impedance control and signal/power conditioning.
Connectors of various types are used to interconnect electrical and
electronic devices, assemblies, units, etc. These connectors are
available in various geometric configurations, i.e. cylindrical,
rectangular, etc., and incorporate various means for electrically
connecting and disconnecting circuit paths. Some connector types
incorporate integral means for EMI filtering and signal/power
conditioning.
The prior art connectors suffer certain disadvantages such as:
limited life in terms of connect and disconnect (mate and unmate)
cycles; deformation of mating parts; contamination of conducting
surfaces; foreign material occluded in connector cavities; large
insertion and extraction forces, often beyond manual capabilities;
large spacing between adjacent connection points; and the
requirement for special repair and inspection tools.
Electromechanical devices, such as relays, have long used contacts
which may be electroplated on and/or mechanically affixed to
compliant meeting parts, often referred to as contact leads. These
contact arrangements generally provide good and long term
reliability in terms of gas-tight connections.
Electroplated spherical "gold bumps" have long been applied in grid
type patterns to the surfaces of various substrates, i.e. printed
circuit boards, ceramic integrated circuit chip carriers, etc. Such
arrangements are frequently used for permanently connecting
electrical and electronic components via lead wires or beams to
circuit paths on or in the substrates.
Compression type interconnect systems or planar contact grid array
connectors employ the aforenoted types of contacts and
electroplated spherical gold bumps. One such interconnect system is
that developed and marketed by the Connecting Devices Division of
the Hughes Aircraft Company under the trade designation GOLD DOT.
The GOLD DOT connector and a connector marketed by TRW Company,
Inc. under the trade designation BUTTON BOARD differ substantially
from arrangements employed for other connectors intended for
repetitive insertions (matings) and extractions (unmatings).
The compression connector arrangements described above and, in
particular, the GOLD DOT arrangement is based on clamping a
spherical noble metal contact, which may be an electrically
deposited gold bump, on the surface of one mating part against a
corresponding noble metal or metal plated pad on the mating
component. These dots and pads are precisely arranged in grid type,
mirror image patterns on their respective mating components. In
use, a minimum of four ounces of clamping force is required for a
gas-tight contact or seal. Therefore, a reasonably sized connector
with 400 contacts requires a total of 1600 ounces or 100 pounds of
force. Small variations in contact surface height must be
accommodated and the total force must be borne uniformly by each
contact pair. In the instant case, each of the 400 contacts must
experience a minimum of 4 ounces of force to assure a gas-tight
connection. This requires that one of the mating connector halves
be sufficiently rigid to resist deformation induced by the forces
concentrated on contact surfaces. The other connector half must
have sufficient compliance so that the individual forces are
concentrated on the contact surfaces, rather than between said
surfaces. Also, this compliance must accommodate small variations
in the height of contact surfaces to avoid non-uniform distribution
of forces among individual contacts.
In the case of the Hughes GOLD DOT connectors, the mating parts
that support the bumps or dots are made of materials usually used
for flexible printed circuits. External connection points and
conducting paths to the dots are also provided on this flexible
substrate material. The corresponding mating part with the pads or
bumps may be made of flexible printed circuit board material, rigid
or semi-rigid printed circuit board material, or ceramic substrate
material. Also, the corresponding part contains the conducting
paths between the pad and external connection points.
Unlike most other interconnect systems, the Hughes GOLD DOT or
other compression contact connectors do not require large forces
during connector engagement and disengagement because the contacts
do not "wipe" each other. That is to say, there is no mechanical
interference involved. To make reliable, low resistance
connections, i.e. gas-tight connections, the two halves of the
connector are precisely aligned and a large compression force is
applied with a clamping type mechanism. Like several low signal or
instrumentation type electric relay contacts, the resulting
pressure at each of the dot/pad connection points is usually large
enough to break any contaminating film or oxide on either or both
surfaces and is sufficient to assure low electrical resistance
paths.
Although the Hughes GOLD DOT interconnect arrangement overcomes
many of the above noted disadvantages and enables connectors to be
more densely populated, i.e. more connection points per unit area,
GOLD DOT connectors have several shortcomings. For example, the
connection of coaxial conductors is not accommodated and in-line
filters, are not accommodated. Further, the capability to handle
substantial electrical currents is not available. In addition, the
clamping mechanism and related structure needed to withstand
deformation and uniformly distribute the required clamping force
for the mating connector halves is generally large and heavy. Since
at least one mating part is made of flexible material and precise
alignment is imperative, more weight and parts are required.
Another weight and size penalty is suffered when ceramics, such as
alumina, are used in mating parts. These parts must be soldered or
bonded to a metal base to survive operating conditions. Also, the
obverse side of either of the parts populated with GOLD DOTS, or
the mating part with gold pads, cannot be used for mounting
components.
SUMMARY OF THE INVENTION
This invention contemplates a planer contact grid array connector
wherein a relatively thin layer of ceramic is selectively applied
to a metal substrate to provide a selectively ceramic coated metal
substrate (SCCMS) suitable for fabrication of thick film hybrid
circuits. This is in contrast to conventional ceramic coated metals
for electronic applications (usually porcelain enameled steel) to
the extent that the SCCMS arrangement is compatible with standard
thick film conductive and resistant inks and processing conditions
used for alumina substrates, a material of usual choice for hybrid
circuit fabrication. The ceramic coating which may be, for example,
of silicon nitride, while chemically different from alumina, has
comparable or better electrical properties, i.e. dielectric
constant and breakdown voltage. Also, when compared to alumina the
SCCMS arrangement is extremely strong, as well as highly resistant
to oxidation and corrosive environments. These properties allow the
SCCMS to be employed in applications which dispense with the usual
protective enclosures, and to be physically integrated with
mechanical devices functioning in hostile environments.
Because the SCCMS can be processed in the same way as alumina,
conventional ceramic-metallic (cermet) thick film conductive and
resistant inks can be employed to build up interconnect networks as
in conventional hybrid circuit fabrication. Other technologies
known in the art can be used to build up additional interconnect
structures on top of the SCCMS/thick film circuitry by alternating
layers of a polymer dielectric with thin film conductors, including
gold bumps and pads, for supplementing thin film processing with
electro-deposition where required to build up additional
thicknesses of metal for contacts or increased current carrying
capacity.
In this regard, reference is made to copending, commonly assigned
U.S. application Ser. No. 432,248, now abandoned and U.S.
application Ser. No. 319,439 which issued as U.S. Pat. No.
4,999,740 on Mar. 12, 1991 as well as to commonly assigned U.S.
application Ser. No. 2,545, (now abandoned).
As earlier indicated, one of the mating connector halves, must have
substantial mechanical stiffness to resist deformation and assure
uniform distribution of a clamping force over all of the mating
contacts. This capability has been previously provided through
heavy ancillary reinforcing means that preclude the use of the
obverse side of the connector half.
There are other limitations inherent in prior art connector
arrangements. These limitations do not allow the connector
arrangements to be used for a variety of applications. One such
limitation is a low current carrying capacity. The prior art
moderately increases current carrying capacity by connecting
several contact pairs in parallel. However, the total current
capacity is limited by the properties of the materials used in both
mating halves of the connector.
The present invention obviates the aforenoted disadvantages of the
prior art connector arrangements.
Accordingly, the present invention contemplates a planer contact
grid array connector whereby contact current carrying capacity is
substantially increased, structural configuration is simplified,
and weight and size are reduced. The described selectively coated
ceramic metal substrate (SCCMS) and the complementary deposition of
multi-layer circuitry on said substrate by a combination of thick
and thin film technology, and a high modulus of elasticity
selectively ceramic coated metal substrate core material that
resists deformation and assures a uniform distribution of force
over all of the mating surfaces, are the key elements in overcoming
the disadvantages of the prior art. Weight and size reduction are
achieved since the SCCMS core material also serves as an integral
part of the structure for aligning the two connector halves and for
applying the clamping forces. A typical arrangement that may be
employed for generating the clamping force includes a cam or
eccentrically mounted circular plate (wheel), on either or both
sides of the connector (depending on clamping force requirements)
actuated by a lever. The clamping force is generated when the cam
or eccentric wheel is rotated and the radius is increased. The
clamping force is a function of the ratio of the actuating lever
length and the eccentric radius.
Structural configuration simplification is achieved since the SCCMS
core is an intrinsic part of a connector half and a clamping force
is necessary only when engaging connector halves so as to reduce
the number of parts. Further, since the metal core is a part of a
connector half, alignment of the two halves is simplified. This
arrangement reduces the complexity of the structure needed to
assure precision alignment of the two halves.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic representation of a planar contact grid
array connector arrangement having a typical array of simple
contacts according to the invention.
FIGS. 2 and 3 are diagrammatic sectional views of a portion of the
connector of FIG. 1, and particularly showing a selectively ceramic
coated metal substrate (SCCMS) with through holes and polymer
dielectric multilayer circuitry according to the invention.
FIG. 4 is a diagrammatic sectional view illustrating the
construction of a simple planer contact grid array connector
according to the invention.
FIG. 5 is a diagrammatic sectional view of a bar-type contact
connector according to the invention.
FIG. 6 is a diagrammatic representation of a planar contact grid
array connector arrangement having a typical array of simple
contacts and coaxial contacts according to the invention.
FIG. 7 is a diagrammatic sectional view of a portion of the
connector of FIG. 6.
FIG. 8 is a diagrammatic representation of a planer contact grid
array connector arrangement having a typical array of simple
contacts, coaxial contacts and active circuitry according to the
invention.
FIG. 9 is a diagrammatic sectional view of a portion of the
connector shown in FIG. 8.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIG. 1, a planar contact grid array connector
arrangement is designated generally by the numeral 1. Arrangement 1
is constructed on a selectively ceramic coated metal substrate
(SCCMS) which will hereinafter be more fully described.
Arrangement 1, has a typical grid array of simple contacts 2.
Circuitry can be applied to both sides of the SCCMS as will be
hereinafter described. Side-to-side interconnecting is accomplished
with conductive through holes 4. Holes 4 may be plated through for
the purposes intended. Holes 4 will further be referred to with
reference to FIG. 3.
Ceramic thick film circuitry is applied directly to the ceramic
surface of the SCCMS and multi-layer circuitry based on polymer
dielectric and thin film metal conductors can optionally be applied
on top of the ceramic thick film circuitry if required, as will
also be hereinafter more fully described. Interlayer connection is
achieved through vias 6 formed in the polymer dielectric.
The foundation material for the arrangement shown in FIG. 1 is the
aforementioned SCCMS in which a ceramic dielectric 8 such as
silicon nitride is applied to a metal core 10 (FIGS. 2 and 3) and
permanently bonded thereto by firing at a high temperature to form
the SCCMS which is designated by the numeral 9.
In regard to SCCMS 9, ceramic dielectric 8 is applied as a coating
to metal core 10 as a thick film ink by conventional screen
printing methods. Core 10 is a suitable metal having a high modulus
of elasticity for the purposes intended. After firing at the
aforenoted high temperatures, the resulting ceramic coating, i.e.
dielectric 8, resembles alumina. This coating is nonporous, rugged
and permanently bonded to the metal on only those areas where the
coating was screen printed. The selective nature of the application
of the coating allows portions of metal core 10 to be uncoated or
left bare. These bare areas provide surfaces or areas for
mechanical attaching or otherwise affixing components to SCCMS 9,
for electrical connections to metal core 10, or for attaching a
SCCMS assembly to external components, other assemblies within a
system, or another system, as the case may be.
Ceramic dielectric 8 is applied to one or both sides of metal core
10 to provide a single or double sided SCCMS 9. A single sided
SCCMS 9 is shown in FIG. 2 and a double sided SCCMS 9 is shown in
FIG. 3. Ceramic thick film circuitry is built up on one or both
sides of SCCMS 9 by conventional methods employing standard thick
film ceramic-metallic (cermet) conductive inks to form thick film
conductor traces such as 11. Electrical connection to metal core 10
can be made through openings formed in the ceramic dielectric for
that purpose.
Interconnection between circuitry on opposite sides of SCCMS 9 is
achieved by conductive through holes 4. Holes 4 are lined with an
insulating layer of a suitable polymer 15 and are metallized by
conventional electroless or electrolytic plating of copper such as
employed in the manufacture of multilayer printed circuit boards.
Holes 4 can be located in areas where ceramic dielectric 8 is
continuous so as to connect a copper (for example) thin film
conductor 13 on one side (FIG. 3) to a thick film conductor 11
(FIG. 2) on the opposite side of holes 4, as will now be
discerned.
Alternatively, holes 4 can be located in an area where ceramic
dielectric 8 is absent so that no side-to-side circuit connection
is made. In this case, through holes 4 accommodate contacts such as
16 that have substantially greater current carrying capacity.
Contacts 16, which are of a noble metal, are affixed via riveting,
as shown in FIG. 3, or by having the shank end of the contact
threaded for a nut to secure the contact to the SCCMS structure
(not otherwise shown). The shank end of the contact also provides
means for connecting large current carrying leads. Also,
male/female contacts may be used when required and the means for
incorporation of said male/female contacts into the assembly is the
same as described above for contact 16.
Multi-layer circuitry employing polymer dielectric layers 18 and
thick film conductors 11 can be built up on top of SCCMS 9 thick
film circuitry by successive applications of the polymer dielectric
followed by vacuum deposition and patterned thin film metallization
to form conductors and pads or contacts. Vias 6 which interconnect
layers of thin film circuitry are formed in the polymer dielectric
layers by a film imaging process followed by metallization.
An alternate arrangement for increasing current carrying capacity
is shown in FIG. 5. In this arrangement noble metal (e.g., gold)
bars are used instead of an array of dots and provide a greater
capacity and allow a current plane to carry current instead of
several conducting paths for that purpose.
The arrangement includes a thick film gold contact bar 22 disposed
in a space 25 between SCCMS 9 including metal core 10 and ceramic
dielectric 18 and a polymer dielectric layer 8, and a plated gold
contact bar 23 disposed within polymer dielectric layer 18. A metal
backing plate 24 is supported by a layer 26 of elastomer or the
like. A clamping force F is applied to metal core 10 of SCCMS 9 and
to backing plate 24. Force F is applied through the aforementioned
cam and eccentrically mounted plate (not shown).
FIG. 4 illustrates the construction of planer contact grid array
connector regions on SCCMS 9. A simple contact grid array connector
is fabricated from an array of thick film gold contact pads and
conductors 28 formed on SCCMS 9 by conventional methods, thus
providing one half of a connector pair. In contrast to alumina, the
SCCMS structure is extremely strong and can readily tolerate the
high clamping forces F required for gas-tight contacts without
significant deformation.
The mating half of the connector shown in FIG. 4 can be of a
conventional flexible or semi-rigid single or multiple layer
printed circuit board material, with electroplated gold contacts or
bumps 30 on one side of a flexible polymer film 32. Bumps 30 are
connected to copper conductors 33 on the opposite side of the
flexible film. Behind the flexible film, is a layer of compliant
elastomer 26 which serves to distribute force F applied by metal
backing plate 24 uniformly over the individual contacts. Elastomer
layer 26 thus serves the same purpose as it does in the arrangement
shown in FIG. 5. Using usual manufacturing techniques, the higher
current carrying capacity contacts may be riveted or otherwise
mechanically attached to this half of the connector as will now be
readily discerned.
FIG. 6 illustrates a planer grid array connector arrangement
designated generally by the numeral 34. Connector arrangement 34 is
similar to connector arrangement 1, except that a coaxial contact
grid array 36 is provided. Otherwise the construction of the
arrangement on SCCMS 9 is as heretofore described with reference to
FIGS. 2-5.
FIG. 7 more particularly illustrates coaxial contact grid array 36
on connector arrangement 34.
Thus, through holes 38 are formed in SCCMS 9 at locations where
coaxial connections are required. These through holes are connected
to circuitry on the SCCMS side of the assembly, opposite the
connector region (the obverse side).
Through holes 38 are insulated from metal core 10 by a layer of
polymer dielectric 40. A shield 42 is formed by electroless or
electrolytic metallization of the polymer dielectric as
aforementioned. That is to say, the metallization method is the
same as conventionally employed for plated through holes in printed
circuit boards.
The center conductor of a coaxial connection is formed by a wire
insert 44 which is insulated from the through hole metallization by
a polymer dielectric 46 filling the resulting annular space. At the
surface, flush with ceramic dielectric 8, an annular pad 48 and a
center pad 50 are formed by thin film deposition of metal. Where
necessary, electrolytic plating is used to build up the contact or
pad to the required thickness.
These pads mate with corresponding pads 52 on the surface of
polymer dielectric 23 on the mating half of the connector pair. The
center conductor pad 50 is connected to a signal line 54 and
annular pad 48 is connected to both shield layers 56 and 58 within
the multi-layer interconnect structure. This structure is an
integral part of half of the connector pair as heretofore
noted.
Forces F are applied as heretofore described with reference to FIG.
4.
FIG. 8 illustrates a planer grid array connector arrangement
designated generally by the numeral 60. Arrangement 60 is similar
to arrangement 34 shown in FIG. 6, except that ceramic thick film
active circuitry 62 is incorporated into the arrangement. The
arrangement is constructed in accordance with FIGS. 2-5 as
heretofore described.
With reference to FIG. 9, ceramic thick film components such as
capacitors are incorporated into circuitry 62 on SCCMS 9 by
printing a high dielectric constant thick film ceramic layer 64
such as, for example, barium titanate between two thick film
ceramic conductor layers 66 and 68. Conductor layers 66 and 68 form
a capacitor 70 integral with SCCMS 9 and part of circuitry 62.
The capacitor or capacitors 70, or other such components such as
resistors, thus formed can be used for electromagnetic interference
(EMI) control, conditioning of signals and power, and for other
functions as part of active circuitry 62, as will now be
discerned.
There has thus been described planer contact grid array connectors
featuring selectively ceramic coated metal substrate (SCCMS)
technology in combination with ceramic thick film and/or
multi-layer thin film circuitry and contacts which may be
electroplated on and/or otherwise affixed to or incorporated in
mating conductor halves. These planer contact array connectors
provide coaxial connection features, increased power handling
capability, and improved means for effecting gas-tight contact
between mating connector halves. Additionally, integral ceramic
thick film components, such as capacitors and resistors for
filtering, impedance control and signal/power conditioning may be
included in the connector structure. The connectors are more
rugged, lighter, smaller and more reliable than other planer
contact array connectors now known in the art.
With the above description of the invention in mind, reference is
made to the claims appended hereto for a definition of the scope of
the invention.
* * * * *